Professor just sent a new pre lab at 11pm for a 9am class tomorrow. Completely lost on how to do this problem and could use some help.
An experiment to find water hardness required 18.2 mL of 0.0050 M EDTA solution to titrate 40.0 mL of tap water using an Eriochrome Black T indicator. Calculate the parts per million calcium present. EDTA reacts with hard water in a 1 to 1 ratio
CHEM LAB HELP: hardness of water, Urgent!?
2018-04-11 12:15 pm
回答 (1)
2018-04-11 1:31 pm
✔ 最佳答案
No. of moles of EDTA reacted = (0.0050 mol/L) × (18.2/1000 L) = 9.1 × 10⁻⁵ molMole ratio EDTA : Ca = 1 : 1
No. of moles of Ca = No. of moles of EDTA = 9.1 × 10⁻⁵ mol
Molar mass of Ca = 40.08 g/mol
Mass of Ca in the water = (9.1 × 10⁻⁵ mol) × (40.08 g/mol) = 3.65 × 10⁻³ g
Density of tap water = 1 g/mL
Mass of 40.0 mL of tap water = (40.0 mL) × (1 g/mL) = 40.0 g
Amount of Ca = [(3.65 × 10⁻³)/40.0] × 10⁶ ppm = 91.3 ppm
收錄日期: 2021-05-01 14:16:33
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